This invention relates to the detection of individuals or objects in delimited spaces each having at least one entrance. By entrance is to be understood in broad terms any door or way through giving access to the delimited space in question. By way of example detection of the presence of individuals during a journey on public transport or during a sports or cultural event taking place in a delimited place is envisaged.
Within the scope of the present invention detection of the presence of individuals or objects is envisaged by means of cards or portable electronic units having means for receiving and transmitting data in the form of electromagnetic signals. It is envisaged that the individuals or objects will be equipped with such portable electronic units.
International application WO 01/03057, incorporated herein by reference, also in the name of the present Applicant, describes one such method of detection, as well as a detection system for individuals or objects in a delimited space having an entrance.
One embodiment of the detection system described in this document is represented in FIG. 1. It is proposed to equip each delimited space, indicated by the reference numeral 10, (for example defined by the compartment 32 of a subway train, a railway carriage, a bus, etc.) with low frequency transmission means 4, 4*, 5, 5* located at the entrance 6 (at each entrance as the case may be). These transmission means are arranged to transmit low frequency electromagnetic signals carrying data to the portable electronic unit (indicated by the reference numeral 36) with which the individual 8 or object is equipped, during the passage of an individual (denoted by the reference numeral 8) or of an object through the entrance 6.
The low frequency transmission means 4, 4*, 5, 5* are arranged to transmit at a relatively low frequency (of the order of a hundred kHz) at least one first low frequency electromagnetic signal within a communication region (formed of communication regions 60, 61, 62 and 63 in the illustration of FIG. 1) essentially covering the entrance 6 to the delimited space 10.
The detection system further comprises high frequency transmission-reception means 12, 13 associated with the delimited space 10 and allowing bidirectional communication at a relatively high frequency (of the order of a hundred MHz or more) to be made with the portable electronic units 36. More precisely, these high frequency transmission-reception means 12, 13 comprise one or more high frequency receivers, here two in number, and one or more high frequency transmitters, also two in number in this example, located in the delimited space 10 in such a manner that the communication regions denoted by the reference numerals 70 and 71 defined by these transmitter-receivers 12, 13 substantially cover the whole area of the delimited space 10 comprising the entrance 6. These communication regions 70, 71 are in particular arranged to encompass the communication regions 61, 62, 63, 64 of the low frequency transmitters 4, 4*, 5, 5* located at the entrances.
Only one delimited space is illustrated in FIG. 1. Nevertheless it will be understood that all the delimited spaces, defined for example by the set of compartments of a subway train or the compartments of the transport means in question, are each equipped with like transmission and reception means.
FIG. 2 shows schematically the structure of one portable unit 36 of the detection system of FIG. 1. This portable electronic unit comprises a low frequency reception module 46 and an antenna 28 for receiving the data transmitted by means of the low frequency electromagnetic signal or signals emitted by the transmission means 4, 4*, 5, 5*, as well as a high frequency transmission-reception module 48 and an antenna 30 for exchanging data with the high frequency transmission-reception means 12, 13 associated with the delimited space 10 by means of a high frequency electromagnetic signal. In fact, as will be described in detail below, a high frequency electromagnetic signal (denoted by the reference C in the following description) is transmitted by the transmission-reception module 48 and a reception acknowledgement (denoted by the reference ACK in the following description) is transmitted by the transmission-reception means 12, 13 associated with the delimited space 10.
An electronic unit 44 for processing data, associated with a memory 45, is connected to the low frequency reception module 46 and the high frequency transmission-reception module 48. The electronic unit 36 is supplied by a power supply source 24 such as a cell or other battery. The data processing unit 44 can preferably be put into a standby mode in order to save power. Likewise the high frequency transmission-reception module 48 is adapted to be deactivated or put into standby by the data processing unit 44, as shown schematically by the interrupter means 50. Accordingly, only the low frequency reception module 46 is permanently or quasi-permanently powered and this activates the data processing unit 44 when a low frequency electromagnetic signal emitted by the low frequency transmission means is received by the receiver module 46.
According to one general mode of operation described in the international application mentioned above, the electronic units 36 are normally in standby mode. In standby mode the data processing unit 44 and the high frequency transmission-reception module are thus deactivated. When an electronic unit 36 in standby mode passes through an entrance of the system, such as the entrance 6 of FIG. 1, this electronic unit 36 is activated by the low frequency electromagnetic field emitted by the transmission means 4, 4*, 5, 5* and receives, via the transmitted low frequency electromagnetic signal or signals, data relating to the delimited space in question (for example identification of the vehicle or of the place entered by the individual or object, the date and time, and as applicable, other parameters relating to the delimited space 10). This data is stored in the memory 45 of the portable electronic unit 36.
When the electronic unit 36 has been activated and has passed through the entrance 6, it starts to communicate at high frequency by means of its high frequency transmission-reception module 48 with the transmission-reception means 12, 13 associated with the delimited space. During this high frequency communication, an identification of the portable electronic unit 36 is in particular transmitted to the transmission-reception means 12, 13 of the delimited space 10 for registration by a controlling computer 20 associated with this delimited space 10 and connected to the low frequency transmission means 4, 4*, 5, 5* as well as to the high frequency transmission-reception means 12, 13. In response the transmission-reception means 12, 13 transmit a reception acknowledgement addressed to the portable electronic unit 36.
The controlling computer 20, or more generally the central processing unit, thus keeps up to date a register containing the information on entry and exit of each electronic unit which has entered into the delimited space 10. In like manner, each portable electronic unit 36 can keep up to date a register of the last entries into and exits from delimited spaces, in particular the time, the date and an identification of each delimited space concerned.
According to a specific mode of operation of the detection system described in the abovementioned international application, each portable electronic unit, once activated by the low frequency electromagnetic field, proceeds to transmit, at least once, a high frequency electromagnetic signal addressed to the high frequency transmitter-receivers 12, 13 pending a reception acknowledgement emanating from these transmission-reception means 12, 13. This high frequency electromagnetic signal, or signal of interrogation of presence, is typically transmitted in a periodic manner and, when the high frequency signal transmitted by the portable electronic unit is no longer received by the high frequency transmission-reception means for a predetermined period of time, it is accepted that this portable electronic unit is no longer present in the interior of the delimited space 10 and the portable electronic unit 36 is then switched to standby mode.
By way of simplification, this first mode of operation will be denoted in the following description by the acronym “BIBO” (Be In Be Out) signifying that the presence or absence of an electronic unit 36 in the delimited space is determined on the basis of a reception by the high frequency transmission-reception means 12, 13 associated with the space 10 of a high frequency electromagnetic signal coming from the portable electronic unit.
According to a specific variant of the detection system described in the abovementioned international application, the transmission means comprise first and second low frequency transmitters, denoted respectively by the reference numerals 4, 4* and 5, 5*, as illustrated specifically in FIG. 1. These first and second transmitters are arranged to transmit respective first and second low frequency electromagnetic signals (denoted by the references A and B respectively in the following description) in first 60, 61 and second 62, 63 communication regions respectively, spatially separated from one another and partially overlapping. These first 60, 61 and second 62, 63 communication regions essentially cover the entrance 6 to the delimited space and are respectively situated towards the exterior and towards the interior of the delimited space 10, such that, when an individual or object enters into the delimited space 10, it firstly encounters the first A and then the second low frequency electromagnetic signal B.
In the illustration of FIG. 1, the first and second transmitters each comprise a pair of transmitters 4 and 4* and 5 and 5* respectively located on one side and the other of the entrance 6. It will nevertheless be understood that these first and second transmitters could each comprise only a single transmitter or even more than two, what matters being that the communication regions defined by these low frequency transmitters cover the zone of passage of individuals or objects through the entrance 6 and allow definition of a succession of spatially separated regions in which distinct signals are transmitted.
The purpose of this arrangement of first and second low frequency transmitters 4, 4* and 5, 5* and of their transmission field is to allow, in addition to waking up the portable electronic units 36, detection of the direction of passage of individuals or objects through the entrance 6. This detection of the direction of passage is detected by determining the order of reception of the first and second low frequency electromagnetic signals A, B transmitted respectively by the transmitters 4, 4* in the communication regions 61, 61 and by the transmitters 5, 5* in the communication regions 62, 63. The detection is accomplished by detection means including the antenna 28, the low frequency reception module 46 and the electronic/data processing unit 44.
One implementation of the passage detection system is described more specifically in European patent application No. 00204758.8 of 29.12.2000 entitled “Système de détection du passage d'un individu ou objet par une entrée-sortie à un espace délimité”, also in the name of the present Applicant.
According to this application, the detection of the direction of passage through the entrance 6 is effected in particular by the electronic unit 36 on the basis of the order of reception of the first and second low frequency electromagnetic signals A, B transmitted at the entrance. The information concerning the direction of passage is for example determined by detecting at least which of the first and second low frequency electromagnetic signals A, B has been received in the first and in the last place during the passage of the individual or object through the entrance 6. This information of direction of passage, namely information of entrance, of exit or information according to which the electronic unit 36 remains located in the interior or in the exterior of the delimited space, is transmitted by the electronic unit 36 in the form of a high frequency electromagnetic signal to the high frequency transmitter-receivers 12, 13. Once the information of direction of passage has been transmitted, the portable electronic unit 36 is again put on standby. In this mode of operation the reception acknowledgement ACK transmitted by the transmitter-receivers 12, 13 may or may not be taken into account by the electronic unit 36. This reception acknowledgement ACK is preferably taken into account by the electronic unit in order to confirm the reception of the high frequency signal C.
For the sake of simplicity, this second mode of operation will be denoted in the following description by the acronym “WIWO” (Walk In Walk Out), signifying that the presence or absence of an electronic unit 36 in the delimited space is determined on the basis of the information on the direction of passage through the entrance 6.
In a typical application of the abovementioned detection system, such as automatic billing of journeys made by users of public transport means, it is desirable to equip the various vehicles of the public transport network with a detection system operating in as optimum a manner as possible, in order to detect the presence or absence of individuals in these various vehicles with high reliability.
Because of practical considerations related in particular to the possibilities of mounting low frequency transmitters located at the entrances to the delimited spaces defined by the compartments of vehicles, it is more or less easy to implement the second mode of operation called WIWO mentioned above, i.e. the mode of operation based on the detection of the direction of passage of the portable electronic units through the entrances. However, if the possibilities of mounting low frequency transmitters at the entrances are limited or hardly adequate to allow reliable detection of the direction of passage through these entrances, the detection system based on the first mode of operation called BIBO mentioned above is then preferably adopted.
It is noted that the second mode of operation WIWO mentioned above is generally preferred and adopted to the extent that is possible, since it only requires a communication of short duration between the electronic units and the transmitter-receivers associated with the delimited space for the purpose of establishing the presence or absence of a portable electronic unit within the delimited space. The first mode of operation BIBO mentioned above typically requires periodic exchanges between the electronic units and the transmitter-receivers associated with the delimited space in order to establish the presence or absence of an electronic unit within this space and it is thus slightly less optimal from the point of view of consumption with comparison to the second WIWO mode of operation.
Up until now, given that the portable electronic units are not themselves in a position to determine a priori if the system operates on the basis of the first or the second mode of operation mentioned above, the BIBO mode of operation or the WIWO mode of operation is adopted by default for the set of delimited spaces under consideration. A compromise is thus made, which is by definition non-optimal.